Enhanced etching processes using remote plasma sources

ABSTRACT

Methods of etching a patterned substrate may include flowing an oxygen-containing precursor into a first remote plasma region fluidly coupled with a substrate processing region. The oxygen-containing precursor may be flowed into the region while forming a plasma in the first remote plasma region to produce oxygen-containing plasma effluents. The methods may also include flowing a fluorine-containing precursor into a second remote plasma region fluidly coupled with the substrate processing region while forming a plasma in the second remote plasma region to produce fluorine-containing plasma effluents. The methods may include flowing the oxygen-containing plasma effluents and fluorine-containing plasma effluents into the processing region, and using the effluents to etch a patterned substrate housed in the substrate processing region.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/771,264, filed Mar. 1, 2013, and titled “Enhanced Etching ProcessesUsing Remote Plasma Sources.”The entire disclosure of that applicationis incorporated by reference herein for all purposes.

TECHNICAL FIELD

The present technology relates to semiconductor processes and equipment.More specifically, the present technology relates to etching processchemistries and systems for improved material removal.

BACKGROUND

Integrated circuits are made possible by processes which produceintricately patterned material layers on substrate surfaces. Producingpatterned material on a substrate requires controlled methods forremoval of exposed material. Chemical etching is used for a variety ofpurposes including transferring a pattern in photoresist into underlyinglayers, thinning layers, or thinning lateral dimensions of featuresalready present on the surface. Often it is sought to have an etchprocess that etches one material faster than another facilitating, forexample, a pattern transfer process. Such an etch process is said to beselective to the first material. As a result of the diversity ofmaterials, circuits, and processes, etch processes have been developedwith a selectivity towards a variety of materials.

A wet HF etch preferentially removes silicon oxide over otherdielectrics and semiconductors. However, wet processes are unable topenetrate some constrained trenches and sometimes deform the remainingmaterial. Dry etches produced in local plasmas formed within thesubstrate processing region can penetrate more constrained trenches andexhibit less deformation of delicate remaining structures. However,local plasmas can damage the substrate through the production ofelectric arcs as they discharge.

Thus, there is a need for improved methods and systems for selectivelyetching materials and structures on semiconductor substrates. These andother needs are addressed by the present technology.

SUMMARY

Methods of etching a patterned substrate may include flowing anoxygen-containing precursor into a first remote plasma region fluidlycoupled with a substrate processing region. The oxygen-containingprecursor may be flowed into the region while forming a plasma in thefirst remote plasma region to produce oxygen-containing plasmaeffluents. The methods may also include flowing a fluorine-containingprecursor into a second remote plasma region fluidly coupled with thesubstrate processing region while forming a plasma in the second remoteplasma region to produce fluorine-containing plasma effluents. Themethods may include flowing the oxygen-containing plasma effluents andfluorine-containing plasma effluents into the processing region, andusing the effluents to etch a patterned substrate housed in thesubstrate processing region.

At least one additional precursor may also be flowed with one or both ofthe oxygen-containing precursor or the fluorine-containing precursor,and the additional precursor may be selected from the group consistingof helium, argon, nitrogen, and molecular hydrogen (H₂). Thefluorine-containing precursor may be selected from the group consistingof atomic fluorine, diatomic fluorine, nitrogen trifluoride, carbontetrafluoride, hydrogen fluoride, and xenon difluoride. Thefluorine-containing precursor may be nitrogen trifluoride inembodiments, and the fluorine-containing plasma effluents may includeNF* and NF₂* species. The fluorine-containing plasma effluents may alsoconsist essentially of NF* and NF₂* species in embodiments. Theoxygen-containing precursor may include a precursor selected from thegroup consisting of molecular oxygen, ozone, nitrous oxide, nitricoxide, and nitrogen dioxide.

The first remote plasma region may be a remote plasma unit separate fromand fluidly coupled with the substrate processing chamber. The secondremote plasma region may be configured to produce a capacitively-coupledplasma located within the processing chamber and fluidly coupled withthe processing region. The plasma in the second remote plasma region maybe operated at a power level of less than or about 500 Watts, and may beoperated at a power level of less than or about 200 Watts inembodiments. The substrate processing region may be plasma-free duringthe etching process. The fluorine-containing precursor may bypass thefirst plasma region in disclosed embodiments. The methods may alsoinclude maintaining the substrate temperature at or below about 100° C.during the etch process, and may include maintaining the substratetemperatures at or below about 50° C. during the etch process.

Methods of etching a patterned substrate may also include flowing anoxygen-containing precursor into a first remote plasma region fluidlycoupled with a second remote plasma region of a substrate processingchamber while forming a plasma in the first remote plasma region toproduce oxygen-containing plasma effluents. The methods may includedelivering the oxygen-containing plasma effluents into the second remoteplasma region. The methods may also include flowing afluorine-containing precursor into the second remote plasma region whileforming a plasma in the second remote plasma region to producefluorine-containing plasma effluents. The second remote plasma regionmay be fluidly coupled with a substrate processing region of theprocessing chamber. The methods may further include delivering theoxygen-containing plasma effluents and fluorine-containing plasmaeffluents into the substrate processing region, and etching a patternedsubstrate housed in the substrate processing region with theoxygen-containing and fluorine-containing plasma effluents.

The fluorine-containing precursor may bypass the first plasma region inthe methods, and the first remote plasma region may be a remote plasmaunit separate from and fluidly coupled with the substrate processingchamber. The plasma in the second remote plasma region may be acapacitively-coupled plasma formed between electrodes within theprocessing chamber. The plasma in the second remote plasma region may beoperated at a power level of less than or about 200 Watts in disclosedembodiments. The methods may further include operating the first remoteplasma region at a first plasma power, and operating the second remoteplasma region at a second plasma power. The first plasma power andsecond plasma power may be different from one another in embodiments.

Methods of etching a patterned substrate may also include flowing anoxygen-containing precursor into a first remote plasma region fluidlycoupled with a second remote plasma region of a substrate processingchamber while forming a plasma in the first remote plasma region toproduce oxygen-containing plasma effluents. The methods may includedelivering the oxygen-containing plasma effluents into the second remoteplasma region. The methods may also include flowing nitrogen trifluorideinto the second remote plasma region through an inlet that bypasses thefirst remote plasma region while forming a capacitively-coupled plasmain the second remote plasma region at a power level of less than orabout 200 Watts to produce NF* and NF₂* plasma effluents. The secondremote plasma region may be fluidly coupled with a substrate processingregion of the processing chamber. The methods may further includedelivering the oxygen-containing plasma effluents and the NF* and NF₂*plasma effluents into the substrate processing region, and etching apatterned substrate housed in the substrate processing region with theplasma effluents. The substrate processing region may be substantiallyplasma-free during the etching, and the patterned substrate may haveexposed regions of silicon oxide and silicon nitride.

Such technology may provide numerous benefits over conventionaltechniques. For example, improved selectivity may be achieved based onmore tunable plasma profiles. Additionally, lower operating powers mayimprove chamber component protection and degradation. These and otherembodiments, along with many of their advantages and features, aredescribed in more detail in conjunction with the below description andattached figures.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the disclosedtechnology may be realized by reference to the remaining portions of thespecification and the drawings.

FIG. 1 shows a flow chart of operations of an etch process according toembodiments of the disclosed technology.

FIG. 2 shows another flow chart of operations of an etch processaccording to embodiments of the disclosed technology.

FIG. 3A shows a schematic cross-sectional view of a substrate processingsystem according to embodiments of the disclosed technology.

FIG. 3B shows a schematic cross-sectional view of a portion of asubstrate processing chamber according to embodiments of the disclosedtechnology.

FIG. 3C shows another schematic cross-sectional view of a portion of asubstrate processing chamber according to embodiments of the disclosedtechnology.

FIG. 3D shows another schematic cross-sectional view of a portion of asubstrate processing chamber according to embodiments of the disclosedtechnology.

FIG. 3E shows a bottom plan view of a showerhead according toembodiments of the disclosed technology.

FIG. 4 shows a top plan view of an exemplary substrate processing systemaccording to embodiments of the disclosed technology.

In the appended figures, similar components and/or features may have thesame numerical reference label. Further, various components of the sametype may be distinguished by following the reference label by a letterthat distinguishes among the similar components and/or features. If onlythe first numerical reference label is used in the specification, thedescription is applicable to any one of the similar components and/orfeatures having the same first numerical reference label irrespective ofthe letter suffix.

DETAILED DESCRIPTION

The present technology includes improved processes and chemistryprofiles for selectively etching materials on patterned semiconductorsubstrates with respect to other materials. While conventional processesmay discuss etch processes, the presently described configurationsutilize multiple plasma configurations to separately excite precursors.The described technology may advantageously minimize recombination ofplasma species by providing shorter flow pathways for select precursors.Additionally, the technology may allow improved plasma profiles byutilizing multiple methods of exciting one or more precursors used inthe etching operations.

The methods may also beneficially reduce the number of species beingflowed through remote plasma units coupled with a processing chamber.For example, precursor fluids for etching may often includefluorine-containing precursors, and oxygen and/or nitrogen-containingprecursors. The plasma cavity of the remote plasma system, as well asthe distribution components to the processing chamber, may be coated orlined to provide protection from the reactive radicals. However, if bothradical species are produced inside the remote plasma unit, the producedplasma effluents may interact differently with the coatings or liningsof the unit. Accordingly, the unit may be degraded over time by theprecursors. In the present technology, however, a single precursor maybe flowed through the remote plasma unit, and thus the unit may bedesigned or coated specifically to protect against degradation fromeffluents of the individual precursors.

The technology also surprisingly shows the advantage that by providingthe precursor species through separate remote plasma systems, thespecific dissociation and plasma characteristics of each fluid can betailored to provide improved etching performance. Additionally, byutilizing a reduced power capacitively-coupled plasma (CCP) within thechamber, chamber degradation can be reduced, which provides improvedprocess performance with less particulate contamination. Accordingly,the systems described herein provide improved flexibility in terms ofchemistry modulation, while also providing improved etching performance.These and other benefits will be described in further detail below.

In order to better understand and appreciate the technology, referenceis now made to FIG. 1, which shows a flow chart of a method 100 of anetching process according to embodiments. Prior to the first operation,a substrate may be patterned leaving exposed regions of silicon, siliconoxide, silicon nitride, as well as other oxides, nitrides, metalsincluding tungsten, copper, titanium, tantalum etc., or othercomponents. Silicon may be amorphous, crystalline, or polycrystalline,in which case it is usually referred to as polysilicon. Previousdeposition and formation processes may or may not have been performed inthe same chamber. If performed in a different chamber, the substrate maybe transferred into the processing chamber for the etch process. Variousfront end processing may have been performed including the formation ofgates, vias, and other structures. The patterned substrate may then bedelivered to a substrate processing region of the processing chamber.

In embodiments, the substrate may already be located in the processingregion if a previous operation was performed in the same chamber inwhich the etch process is to occur. An oxygen-containing precursor maybe flowed into a first remote plasma region fluidly coupled with thesubstrate processing region at operation 110, while a plasma is formedin the first remote plasma region to produce oxygen-containing plasmaeffluents. The oxygen-containing precursor may include a variety ofoxygen compounds, and may include one of more precursors such asmolecular oxygen, ozone, nitrous oxide (N₂O), nitric oxide (NO),nitrogen dioxide (NO₂), among other oxygen-containing precursors. Theprecursor may be dissociated in the plasma to produce a variety ofplasma effluents that may include O*, NO*, and other species useful inetching operations.

A fluorine-containing precursor may be flowed into a second remoteplasma region that is separate from, but fluidly coupled with, theprocessing region at operation 120. A plasma may be formed in the secondremote plasma region during the precursor delivery, and the plasma maybe used to produce fluorine-containing plasma effluents. Several sourcesof fluorine may be used in the process, and in general, afluorine-containing precursor may be flowed into the second remoteplasma region that includes at least one precursor selected from thegroup consisting of atomic fluorine, diatomic fluorine, nitrogentrifluoride, carbon tetrafluoride, hydrogen fluoride, and xenondifluoride. The fluorine-containing precursor may include nitrogentrifluoride, and the fluorine-containing plasma effluents that areproduced may include NF* and NF₂* species. As will be explained furtherbelow, the plasma created in the second remote plasma region may bespecifically configured to excite the fluorine-containing precursor insuch a way as to limit radical fluorine species or F* species such thatthe fluorine-containing plasma effluents consist essentially of NF* andNF₂* species.

Either or both of the first and second remote plasma regions may bereferred to as a remote plasma region herein and may be within adistinct module from the processing chamber, or as a compartment ordefined area within the processing chamber. A plasma may be formedwithin the remote plasma region to generate plasma effluents from theoxygen-containing and fluorine-containing precursors. At operation 130,the oxygen-containing plasma effluents and the fluorine-containingplasma effluents may be flowed into the processing region of thechamber. The patterned substrate may be selectively etched with thecombination of oxygen-containing and fluorine-containing plasmaeffluents at operation 140 so that exposed materials on the substratemay be etched.

After the etching has been performed, the reactive chemical species maybe removed from the substrate processing region, and then the substratemay be removed from the processing region. When performed insubstantially this fashion, the methods may allow a region of siliconnitride to be etched at a faster rate than a region of silicon orsilicon oxide. Using the gas phase dry etch processes described herein,established etch selectivities of over 2:1 with regard to the siliconnitride etch rate as compared to the etch rate of other materials suchas silicon and/or silicon oxide are possible. The silicon nitride etchrate may exceed the silicon and/or silicon oxide etch rate by amultiplicative factor of up to or about 5 or more, about 10 or more,about 15 or more, about 20 or more, about 50 or more, about 75 or more,about 100 or more, etc. or greater in embodiments of the technology.

The gas flow ratios of the precursors may include a variety of flowratios such as atomic flow ratios (O:F) less than, greater than, orabout 1:1000, 1:500, 1:250, 1:100, 1:50, 1:25, 1:15, 1:10, 1:5, 1:1,5:1, 10:1, 15:1, 25:1, 50:1, 100:1, 250:1, 500:1, 1000:1, etc. One ormore additional precursors may be delivered with either or both of theoxygen-containing and/or fluorine containing precursors. The additionalprecursors may include relatively inert gases and may be one or moreprecursors selected from the group consisting of helium, argon,nitrogen, and molecular hydrogen (H₂). The inert gas can be used toimprove plasma stability and/or to carry liquid precursors to the remoteplasma region.

Flow rates and ratios of the different gases may be used to control etchrates and etch selectivity. In embodiments, the fluorine-containingprecursor may include NF₃ at a flow rate of between about 1 sccm(standard cubic centimeters per minute) and 5,000 sccm. Theoxygen-containing precursor may be included at a flow rate of betweenabout 1 sccm and 5,000 sccm, and one or more carrier gases at a flowrate of between about 0 sccm and 3000 sccm, may be included with eitherprecursor stream. The atomic flow rates or ratio of O:F may be kept highin embodiments to reduce or eliminate solid residue formation on thesubstrate materials such as oxide. The formation of solid residue mayconsume some silicon oxide which may reduce the silicon selectivity ofthe etch process.

An ion suppressor may be used to filter ions from the plasma effluentsduring transit from the remote plasma regions to the substrateprocessing region in embodiments of the technology. The ion suppressorfunctions to reduce or eliminate ionically charged species travelingfrom the plasma generation region to the substrate. Uncharged neutraland radical species may pass through the openings in the ion suppressorto react at the substrate. It should be noted that complete eliminationof ionically charged species in the reaction region surrounding thesubstrate is not always the desired goal. In many instances, ionicspecies are required to reach the substrate to perform the etch and/ordeposition process. In these instances, the ion suppressor helps controlthe concentration of ionic species in the reaction region at a levelthat assists the process. In embodiments the upper plate of the gasdistribution assembly may include an ion suppressor.

During the etching process, the substrate may be maintained at or belowabout 400° C., and may be maintained at or below about 300° C., 200° C.,100° C., 80° C., 75° C., 50° C., 25° C., 10° C., 0° C., or less. Theprocessing chamber may be maintained at or below about 100 Torr duringthe processes, and may be maintained at or below about 50 Torr, 25 Torr,15 Torr, 5 Torr, 1 Torr, 0.1 Torr, etc., or between about 0.1 mTorr andabout 10 Torr. By maintaining the substrate temperature at lowertemperatures, such as about 10° C. or less, and maintaining the processchamber at a pressure below about 10 Torr, the amount of oxide removalcan be further limited during the removal of silicon nitride.

As mentioned above, the first and second remote plasma regions may befluidly coupled with the substrate processing region to deliver theplasma effluents to the processing region, while the processing regionis plasma-free during the etching process. The substrate processingregion may be described herein as plasma-free during the etch of thepatterned substrate. Plasma-free does not necessarily mean the region isdevoid of plasma. Ionized species and free electrons created within theplasma region may travel through pores or apertures in the showerhead ormanifold, but the region in which the substrate resides is notsubstantially excited by the plasma power applied to the plasma region.The borders of the plasma in the chamber plasma region are hard todefine and may encroach upon the substrate processing region through theapertures in the showerhead. In the case of an inductively-coupledplasma, a small amount of ionization may be effected within thesubstrate processing region directly.

The first and second remote plasma regions may be similar or differentfrom one another in disclosed embodiments. The first remote plasmaregion may be a remote plasma unit (“RPS unit”) that is separate fromthe processing chamber, and that may be fluidly coupled with thechamber. The remote unit may be operated at power levels from betweenbelow or about 10 W up to above or about 10 or 15 kW in variousembodiments. The power and plasma profile of the RPS unit mayadvantageously be tuned to the particular precursor used, such as theoxygen-containing precursor. In this way, the unit may be operated at apower level designed for a degree of dissociation of the precursor. TheRPS unit processing the oxygen-containing precursor may be operated at amuch higher power level as a more complete dissociation may be desiredto produce O* and NO* species, for example. Accordingly, the RPS unitmay be operated between up to or above about 1000 W and up to or aboveabout 10 kW or more. The RF frequency applied in the exemplaryprocessing system may be low RF frequencies less than about 500 kHz,high RF frequencies between about 10 MHz and about 15 MHz or microwavefrequencies greater than or about 1 GHz in embodiments. As such, the RPSunit may be configured to operate at a first power level that isselected based on the composition of the first precursor.

The second remote plasma region may be located within a portion of theprocessing chamber that is maintained separate from the substrateprocessing region. For example, the second remote plasma region may bedefined within the chamber and separated from the processing region witha showerhead or manifold. The second remote plasma region may be acapacitively-coupled plasma (“CCP”) formed within the region. Indisclosed configurations the second remote plasma region may be locatedfluidly between the first remote plasma region and the processingregion. The second remote plasma region may be defined by two or moreelectrodes that allow a plasma to be formed within the region. Thefluorine-containing precursor may be delivered into the second remoteplasma region, and may be delivered so as to bypass the first plasmaregion.

In exemplary embodiments, dissociation of the fluorine-containingprecursor may be caused to a different degree than the dissociation ofthe oxygen-containing precursor. The fluorine-containing precursor mayhave weaker bond energy of the precursor molecules, or a lower degree ofdissociation may be required, and thus the plasma may be formed at adifferent level of power within the second remote plasma region.Improved etching profiles may advantageously be effected when afluorine-containing precursor is only partially dissociated. Forexample, when a fluorine-containing precursor is completely dissociated,the F* radical species may attack the chamber walls and/or the substratedetrimentally. However, when a fluorine-containing precursor, such asnitrogen trifluoride for example, is partially dissociated into NF* andNF₂* species, the chamber and substrate may be less affected whilespecific etching is performed. Accordingly, the CCP may be operated at alower power level to produce only partial dissociation of thefluorine-containing precursor.

The partial dissociation may reduce the amount of F* radical species sothat the fluorine-containing plasma effluents consist essentially of NF*and NF₂* species. For example, although some F* and unexcited NF₃species may be present if the fluorine-containing precursor is nitrogentrifluoride, these species may be minimized in the effluents directedinto the processing region of the chamber. For example, having thefluorine-containing plasma effluents consist essentially of NF* and NF₂*may mean that they comprise at least about 75% of the mix of speciesderived from the fluorine-containing precursor delivered into theprocessing region. Consisting essentially of NF* and NF₂* may also meanthat the two species comprise at least about 80%, 85%, 90%, 95%, 99%,99.9%, etc. or more of the mix of species derived from thefluorine-containing precursor delivered into the processing region. Ifother precursors are utilized that include other species than nitrogen,such as xenon difluoride, for example, the same considerations may applysuch that fully dissociated F* species are minimized.

Operating a conventional CCP may degrade the chamber components, whichmay remove particles that may be inadvertently distributed on asubstrate. Such particles may affect performance of devices formed fromthese substrates due to the metal particles that may provideshort-circuiting across semiconductor substrates. However, the CCP ofthe disclosed technology may be operated at reduced or substantiallyreduced power because the CCP may be utilized only to partiallydissociate the fluorine-containing precursor and/or maintain theoxygen-containing plasma effluents, and not to fully ionize specieswithin the plasma region. For example, the CCP may be operated at apower level below or about 1 kW, 500 W, 250 W, 200 W, 150 W, 100 W, 50W, 20 W, etc. or less. Moreover, the CCP may produce a flat plasmaprofile which may provide a uniform plasma distribution within thespace. As such, a more uniform plasma may be delivered downstream to theprocessing region of the chamber providing improved etching profilesacross a substrate.

Additionally, by providing an additional plasma source, such as the CCPsource, the plasma particles produced in the RPS unit may be continuedor enhanced, and the rate of recombination may be further tuned. Forexample, the oxygen-containing plasma effluents may be delivered intothe second remote plasma region in which the CCP is formed. The plasmain this second remote plasma region may maintain the level ofdissociation produced within the RPS and prevent the plasma effluentsfrom recombining prior to entering the processing region of the chamber.

Turning to FIG. 2 is shown another flow chart of a method 200 ofoperations of an etch process according to disclosed embodiments. Themethod 200 may include one or more of the operations as previouslydiscussed in relation to FIG. 1. The method may include flowing anoxygen-containing precursor into a first remote plasma region fluidlycoupled with a second remote plasma region of a substrate processingchamber while forming a plasma in the first remote plasma region toproduce oxygen-containing plasma effluents at operation 210. The firstremote plasma region may be an RPS unit separate from the processingchamber as previously discussed and fluidly coupled with the processingchamber, or may be a portion of the chamber partitioned from otherregions of the chamber. At operation 220, the oxygen-containing plasmaeffluents may be delivered into the second remote plasma region, whichmay be a partitioned portion of the processing chamber.

A fluorine-containing precursor may be flowed into the second remoteplasma region while forming a plasma therein to producefluorine-containing plasma effluents at operation 230. The second remoteplasma region may be fluidly coupled with the substrate processingregion of the chamber, and may be physically separated by an electrodeat least partially defining the second remote plasma region. Theoxygen-containing plasma effluents and fluorine-containingprecursor/plasma effluents may be allowed to mix within the secondremote plasma region to produce a more uniform mixture of species. Theoxygen-containing plasma effluents and fluorine-containing plasmaeffluents may be delivered into the substrate processing region atoperation 240. A showerhead, ion suppressor, manifold, or other dividermaterial may be positioned between the second remote plasma region andthe processing region of the chamber and may act both as an electrodefor the second remote plasma region as well as a mechanism by which theprecursors are delivered into the processing region. The showerhead mayfurther mix the precursors to improve the uniformity across the profile.The plasma effluents may be used to etch the patterned substrate atoperation 250.

The fluorine-containing precursor may be delivered directly into thesecond remote plasma region to bypass the first remote plasma region. Inthis way, a different plasma profile may be used for thefluorine-containing precursor than with the oxygen-containing precursorto affect the dissociation or plasma profile of the precursor. Thesecond remote plasma region may be a CCP formed between electrodes orchamber components defining the second remote plasma region. The CCP maybe operated at power levels of less than or about 200 Watts aspreviously discussed to provide limited or partial dissociation of thefluorine-containing precursor delivered into the second remote plasmaregion.

Operation of the first and second remote plasma regions may be similaror different in disclosed embodiments. For example, completedissociation of the oxygen-containing precursor may be desired, or agreater level of dissociation, or more energy may be needed to break thebonds of the precursors. Accordingly, the first remote plasma region maybe operated at a first plasma power. The second remote plasma region maybe operated at a lower power to provide a limited amount of dissociationof the fluorine-containing precursor. These two power levels may bedifferent from one another, and the second remote plasma region plasmamay be operated at a power level below the level for the first remoteplasma region.

Performing the methods in such a fashion may provide an additionalbenefit by reducing operating power of the process. Not only will theCCP operated at lower levels produce the fluorine-containing plasmaeffluents, but the oxygen-containing plasma effluents delivered into thesecond remote plasma region may interact with the fluorine-containingprecursor to aid the dissociation of the precursor to produce thefluorine-containing plasma effluents. By utilizing the combinedprocesses, nitrides such as silicon nitride may be etched faster thansilicon, silicon oxide, and other materials exposed on the substrate. Aswould be understood, additional modifications to chamber pressure andplasma power may be used to further tune the etching processes as may berequired. Advantageously, tuning these processes may be performedwithout the need to break vacuum conditions or move the substrate to anadditional chamber. This may reduce overall processing times and savecosts over conventional techniques. Additional examples of etch processparameters, chemistries, and components are disclosed in the course ofdescribing an exemplary processing chamber and system below.

Exemplary Processing System

FIG. 3A shows a cross-sectional view of an exemplary process systemsection 300 with partitioned plasma generation regions within theprocessing chamber. During film etching, e.g., titanium nitride,tantalum nitride, tungsten, silicon, polysilicon, silicon oxide, siliconnitride, silicon oxynitride, silicon oxycarbide, etc., a process gas maybe flowed into the first plasma region 315 through a gas inlet assembly305. The plasma region 315 within the chamber may be similar to thesecond remote plasma region discussed previously, and may be remote fromprocessing region 333 as discussed below. A remote plasma system (“RPS”)301 may be included in the system, and may process a first gas whichthen travels through gas inlet assembly 305. RPS unit 301 may be similarto the first remote plasma region as previously discussed. The inletassembly 305 may include two or more distinct gas supply channels wherethe second channel may bypass the RPS 301, as will be discussed withregard to FIGS. 3B and 3C below. Accordingly, in disclosed embodimentsat least one of the precursor gases may be delivered to the processingchamber in an unexcited state, such as the fluorine-containingprecursor. In another example, the first channel provided through theRPS may be used for the oxygen-containing precursor and the secondchannel bypassing the RPS may be used for the fluorine-containingprecursor in disclosed embodiments. The oxygen-containing precursor maybe excited within the RPS 301 prior to entering the first plasma region315. Accordingly, the fluorine-containing precursor and/or theoxygen-containing precursor as discussed above, for example, may passthrough RPS 301 or bypass the RPS unit in disclosed embodiments. Variousother examples encompassed by this arrangement will be similarlyunderstood.

A cooling plate 303, faceplate 317, ion suppressor 323, showerhead 325,and a substrate support 365, having a substrate 355 disposed thereon,are shown and may each be included according to disclosed embodiments.The pedestal 365 may have a heat exchange channel through which a heatexchange fluid flows to control the temperature of the substrate. Thisconfiguration may allow the substrate 355 temperature to be cooled orheated to maintain relatively low temperatures, such as between about−20° C. to about 200° C., or therebetween. The heat exchange fluid maycomprise ethylene glycol and/or water. The wafer support platter of thepedestal 365, which may comprise aluminum, ceramic, or a combinationthereof, may also be resistively heated to achieve relatively hightemperatures, such as from up to or about 100° C. to above or about1100° C., using an embedded resistive heater element. The heatingelement may be formed within the pedestal as one or more loops, and anouter portion of the heater element may run adjacent to a perimeter ofthe support platter, while an inner portion runs on the path of aconcentric circle having a smaller radius. The wiring to the heaterelement may pass through the stem of the pedestal 365, which may befurther configured to rotate.

The faceplate 317 may be pyramidal, conical, or of another similarstructure with a narrow top portion expanding to a wide bottom portion.The faceplate 317 may additionally be flat as shown and include aplurality of through-channels used to distribute process gases. Plasmagenerating gases and/or plasma excited species, depending on use of theRPS 301, may pass through a plurality of holes, shown in FIG. 3D, infaceplate 317 for a more uniform delivery into the first plasma region315.

Exemplary configurations may include having the gas inlet assembly 305open into a gas supply region 358 partitioned from the first plasmaregion 315 by faceplate 317 so that the gases/species flow through theholes in the faceplate 317 into the first plasma region 315. Structuraland operational features may be selected to prevent significant backflowof plasma from the first plasma region 315 back into the supply region358, gas inlet assembly 305, and fluid supply system 310. The structuralfeatures may include the selection of dimensions and cross-sectionalgeometries of the apertures in faceplate 317 to deactivateback-streaming plasma. The operational features may include maintaininga pressure difference between the gas supply region 358 and first plasmaregion 315 that maintains a unidirectional flow of plasma through theshowerhead 325. The faceplate 317, or a conductive top portion of thechamber, and showerhead 325 are shown with an insulating ring 320located between the features, which allows an AC potential to be appliedto the faceplate 317 relative to showerhead 325 and/or ion suppressor323, which may be electrically coupled with the showerhead 325, orsimilarly insulated. The insulating ring 320 may be positioned betweenthe faceplate 317 and the showerhead 325 and/or ion suppressor 323enabling a capacitively-coupled plasma (“CCP”) to be formed in the firstplasma region. A baffle (not shown) may additionally be located in thefirst plasma region 315, or otherwise coupled with gas inlet assembly305, to affect the flow of fluid into the region through gas inletassembly 305.

The ion suppressor 323 may comprise a plate or other geometry thatdefines a plurality of apertures throughout the structure that areconfigured to suppress the migration of ionically-charged species out ofthe plasma excitation region 315 while allowing uncharged neutral orradical species to pass through the ion suppressor 323 into an activatedgas delivery region between the suppressor and the showerhead. Indisclosed embodiments, the ion suppressor 323 may comprise a perforatedplate with a variety of aperture configurations. These uncharged speciesmay include highly reactive species that are transported with lessreactive carrier gas through the apertures. As noted above, themigration of ionic species through the holes may be reduced, and in someinstances completely suppressed. Controlling the amount of ionic speciespassing through the ion suppressor 323 may provide increased controlover the gas mixture brought into contact with the underlying wafersubstrate, which in turn may increase control of the deposition and/oretch characteristics of the gas mixture. For example, adjustments in theion concentration of the gas mixture can significantly alter its etchselectivity, e.g., SiNx:SiOx etch ratios, SiN:S etch ratios, etc. Inalternative embodiments in which deposition is performed, it can alsoshift the balance of conformal-to-flowable style depositions fordielectric materials.

The plurality of holes in the ion suppressor 323 may be configured tocontrol the passage of the activated gas, i.e., the ionic, radical,and/or neutral species, through the ion suppressor 323. For example, theaspect ratio of the holes, or the hole diameter to length, and/or thegeometry of the holes may be controlled so that the flow ofionically-charged species in the activated gas passing through the ionsuppressor 323 is reduced. The holes in the ion suppressor 323 mayinclude a tapered portion that faces the plasma excitation region 315,and a cylindrical portion that faces the showerhead 325. The cylindricalportion may be shaped and dimensioned to control the flow of ionicspecies passing to the showerhead 325. An adjustable electrical bias mayalso be applied to the ion suppressor 323 as an additional means tocontrol the flow of ionic species through the suppressor.

The ion suppression element 323 may function to reduce or eliminate theamount of ionically charged species traveling from the plasma generationregion to the substrate. Uncharged neutral and radical species may stillpass through the openings in the ion suppressor to react with thesubstrate. It should be noted that the complete elimination of ionicallycharged species in the reaction region surrounding the substrate may notalways be the desired goal. In many instances, ionic species arerequired to reach the substrate to perform the etch and/or depositionprocess. In these instances, the ion suppressor may help to control theconcentration of ionic species in the reaction region at a level thatassists the process.

Showerhead 325 in combination with ion suppressor 323 may allow a plasmapresent in chamber plasma region 315 to avoid directly exciting gases insubstrate processing region 333, while still allowing excited species totravel from chamber plasma region 315 into substrate processing region333. In this way, the chamber may be configured to prevent the plasmafrom contacting a substrate 355 being etched. This may advantageouslyprotect a variety of intricate structures and films patterned on thesubstrate, which may be damaged, dislocated, or otherwise warped ifdirectly contacted by a generated plasma. Additionally, when plasma isallowed to contact the substrate or approach the substrate level, therate at which oxide species etch may increase. Accordingly, if theexposed material is oxide, this material may be further protected bymaintaining the plasma remotely from the substrate.

The processing system may further include a power supply 340electrically coupled with the processing chamber to provide electricpower to the faceplate 317, ion suppressor 323, showerhead 325, and/orpedestal 365 to generate a plasma in the first plasma region 315 orprocessing region 333. The power supply may be configured to deliver anadjustable amount of power to the chamber depending on the processperformed. Such a configuration may allow for a tunable plasma to beused in the processes being performed. Unlike a remote plasma unit,which is often presented with on or off functionality, a tunable plasmamay be configured to deliver a specific amount of power to the plasmaregion 315. This in turn may allow development of particular plasmacharacteristics such that precursors may be dissociated in specific waysto enhance the etching profiles produced by these precursors. Forexample, this may provide the partial dissociation of nitrogentrifluoride as explained previously.

A plasma may be ignited either in chamber plasma region 315 aboveshowerhead 325 or substrate processing region 333 below showerhead 325.A plasma may be present in chamber plasma region 315 to produce theradical-fluorine precursors from an inflow of the fluorine-containingprecursor. An AC voltage typically in the radio frequency (“RF”) rangemay be applied between the conductive top portion of the processingchamber, such as faceplate 317, and showerhead 325 and/or ion suppressor323 to ignite a plasma in chamber plasma region 315 during deposition.An RF power supply may generate a high RF frequency of 13.56 MHz but mayalso generate other frequencies alone or in combination with the 13.56MHz frequency.

Plasma power can be of a variety of frequencies or a combination ofmultiple frequencies. In the exemplary processing system the plasma maybe provided by RF power delivered to faceplate 317 relative to ionsuppressor 323 and/or showerhead 325. The RF power may be between about10 Watts and about 2000 Watts, between about 100 Watts and about 2000Watts, between about 200 Watts and about 1500 Watts, between about 0 andabout 500 Watts, or between about 200 Watts and about 1000 Watts indifferent embodiments. The RF frequency applied in the exemplaryprocessing system may be low RF frequencies less than about 200 kHz,high RF frequencies between about 10 MHz and about 15 MHz, or microwavefrequencies greater than or about 1 GHz in different embodiments. Theplasma power may be capacitively-coupled or inductively-coupled into theremote plasma region. In alternative configurations, the chamber may beconfigured to utilize UV or e-beam sources to excite or activate thereactive species. These capabilities may be utilized in conjunction withor in lieu of the plasma.

The top plasma region 315 may be left at low or no power when a bottomplasma in the substrate processing region 333 is turned on to, forexample, cure a film or clean the interior surfaces bordering substrateprocessing region 333. A plasma in substrate processing region 333 maybe ignited by applying an AC voltage between showerhead 355 and thepedestal 365 or bottom of the chamber. A cleaning gas may be introducedinto substrate processing region 333 while the plasma is present.

A fluid, such as a precursor, for example a fluorine-containingprecursor, may be flowed into the processing region 333 by embodimentsof the showerhead described herein. Excited species derived from theprocess gas in the plasma region 315 may travel through apertures in theion suppressor 323, and/or showerhead 325 and react with an additionalprecursor, such as an oxygen-containing precursor, flowing into theprocessing region 333 through the showerhead. Alternatively, if allprecursor species are being excited in plasma region 315, no additionalprecursors may be flowed through the separate portion of the showerhead.Little or no plasma may be present in the processing region 333. Excitedderivatives of the precursors may combine in the region above thesubstrate and, on occasion, on the substrate to etch structures orremove species on the substrate in disclosed applications.

Exciting the fluids in the first plasma region 315 directly, or excitingthe fluids in the RPS units 301, may provide several benefits. Theconcentration of the excited species derived from the fluids may beincreased within the processing region 333 due to the plasma in thefirst plasma region 315. This increase may result from the location ofthe plasma in the first plasma region 315. The processing region 333 maybe located closer to the first plasma region 315 than the remote plasmasystem (RPS) unit 301, leaving less time for the excited species toleave excited states through collisions with other gas molecules, wallsof the chamber, and surfaces of the showerhead.

The uniformity of the concentration of the excited species derived fromthe process gas may also be increased within the processing region 333.This may result from the shape of the first plasma region 315, which maybe more similar to the shape of the processing region 333. Excitedspecies created in the RPS 301 may travel greater distances to passthrough apertures near the edges of the showerhead 325 relative tospecies that pass through apertures near the center of the showerhead325. The greater distance may result in a reduced excitation of theexcited species and, for example, may result in a slower etch rate nearthe edge of a substrate. Exciting the fluids in the first plasma region315 may mitigate this variation for the fluid flowed through RPS 301, oralternatively bypassed around the RPS unit.

The processing gases may be excited in first plasma region 315 and maybe passed through the showerhead 325 to the processing region 333 in theexcited state. While a plasma may be generated in the processing region333, a plasma may alternatively not be generated in the processingregion. In one example, the only excitation of the processing gas orprecursors may be from exciting the processing gases in RPS 301 andplasma region 315 to react with one another in the processing region333. As previously discussed, this may be to protect the structurespatterned on the substrate 355.

In addition to the fluid precursors, there may be other gases introducedat varied times for varied purposes, including carrier gases to aiddelivery. A treatment gas may be introduced to remove unwanted speciesfrom the chamber walls, the substrate, the deposited film and/or thefilm during deposition. A treatment gas may be excited in a plasma andthen used to reduce or remove residual content inside the chamber. Inother disclosed embodiments the treatment gas may be used without aplasma. When the treatment gas includes water vapor, the delivery may beachieved using a mass flow meter (MFM), an injection valve, or bycommercially available water vapor generators. The treatment gas may beintroduced to the processing region 233, either through the RPS unit orbypassing the RPS unit, and may further be excited in the first plasmaregion.

FIGS. 3B and 3C show exemplary detailed views of the features of inletassembly 305 providing the one or more precursors to the processingchamber. As shown in FIG. 3B, a first and second precursor may bedelivered through separate channels in inlet assembly 305 b. Forexample, an oxygen-containing precursor that has been activated in RPSunit 301 may travel into inlet assembly 305 and along channel 306 atoward gas supply region 358 for delivery into plasma region 315.Channel 306 a may be an exterior channel having an annular orsemi-annular shape around an interior channel 308 a that may provide afluid path for a second precursor that may bypass RPS unit 301. Forexample, a fluorine-containing precursor may be delivered via channel308 a toward plasma region 315. Channel 308 a may extend past gas supplyregion 358 to deliver the precursor directly into plasma region 315, orit may alternatively deliver a precursor into gas supply region 358 forinitial mixing with the precursor delivered along path 306 a.

FIG. 3C illustrates an additional embodiment of the inlet assembly 305and delivery channels 306 b and 308 b. As shown, the precursors may beseparately delivered into a lower region 310 of inlet assembly 305 cwhere they may be allowed to initially interact before reaching gassupply region 358. For example, an oxygen-containing precursor may bedelivered from RPS unit 301 into inlet assembly 305 along channel 306 b,while a fluorine-containing precursor may be delivered so as to bypassRPS unit 301 and into inlet assembly 305 along channel 308 b. Channels306 b and 308 b may deliver the precursors into lower region 311 ofinlet assembly 305 c where the precursors interact and mix prior toentering gas supply region 358. Lower region 311 may include channels orflow paths bored or formed within the walls defining the region 311 soas to improve mixing and increase turbulent flow of the fluids enteringthe gas supply region 358. For example, flow lines similar to riflingmay be etched within the lower region 311 to cause the precursors orplasma effluents to swirl and mix prior to entering the gas supplyregion 358.

FIG. 3D shows a detailed view of the features 353 affecting theprocessing gas distribution through faceplate 317. As shown in FIGS. 3Aand 3D, faceplate 317, cooling plate 303, and gas inlet assembly 305intersect to define a gas supply region 358 into which process gases maybe delivered from gas inlet 305. The gases may fill the gas supplyregion 358 and flow to first plasma region 315 through apertures 359 infaceplate 317. The apertures 359 may be configured to direct flow in asubstantially unidirectional manner such that process gases may flowinto processing region 333, but may be partially or fully prevented frombackflow into the gas supply region 358 after traversing the faceplate317.

The gas distribution assemblies such as showerhead 325 for use in theprocessing chamber system 300 may be referred to as dual channelshowerheads (“DCSH”) and are additionally detailed in the embodimentsdescribed in FIG. 3A as well as FIG. 3E herein. The dual channelshowerhead may provide for etching processes that allow for separationof etchants outside of the processing region 333 to provide limitedinteraction with chamber components and each other prior to beingdelivered into the processing region.

The showerhead 325 may comprise an upper plate 314 and a lower plate316. The plates may be coupled with one another to define a volume 318between the plates. The coupling of the plates may be so as to providefirst fluid channels 319 through the upper and lower plates, and secondfluid channels 321 through the lower plate 316. The formed channels maybe configured to provide fluid access from the volume 318 through thelower plate 316 via second fluid channels 321 alone, and the first fluidchannels 319 may be fluidly isolated from the volume 318 between theplates and the second fluid channels 321. The volume 318 may be fluidlyaccessible through a side of the gas distribution assembly 325. Forexample, an additional precursor that may not interact with theactivated precursors previously described may be delivered to theprocessing region via second fluid channels 321 so that the activatedprecursors and the additional precursors interact only when theyseparately enter the processing region 333. Although the exemplarysystem of FIG. 3 includes a DCSH, it is understood that alternativedistribution assemblies may be utilized that maintain first and secondprecursors fluidly isolated prior to the processing region 333. Forexample, a perforated plate and tubes underneath the plate may beutilized, although other configurations may operate with reducedefficiency or not provide as uniform processing as the dual-channelshowerhead as described. Alternatively, when the only precursorsutilized will be delivered via inlet assembly 305, and all precursorswill flow from plasma region 315, a DCSH may not be necessary, and asingle plate manifold or perforated plate may be utilized that furthermixes the precursors while delivering them directly to the processingregion 333.

In the embodiment shown, showerhead 325 may distribute via first fluidchannels 319 process gases which contain plasma effluents uponexcitation by a plasma in chamber plasma region 315 and/or RPS unit 301.In embodiments, the process gas introduced into the RPS 301 may includean oxygen-containing precursor and the precursors delivered into chamberplasma region 315 may contain fluorine, e.g., CF₄, NF₃ or XeF₂. Theprecursors may also include one or more carrier gases such as helium,argon, nitrogen (N₂), etc. Plasma effluents may include ionized orneutral derivatives of the process gas and may also be referred toherein as a radical-fluorine precursor referring to the atomicconstituent of the process gas introduced.

FIG. 3E is a bottom view of a showerhead 325 and lower plate 316 for usewith a processing chamber according to disclosed embodiments. Showerhead325 corresponds with the showerhead shown in FIG. 3A. Through-holes 331,which show a view of first fluid channels 319, may have a plurality ofshapes and configurations in order to control and affect the flow ofprecursors through the showerhead 325. Small holes 327, which show aview of second fluid channels 321, may be distributed substantiallyevenly over the surface of the showerhead, even amongst thethrough-holes 331, which may help to provide more even mixing of theprecursors as they exit the showerhead than other configurations.

The chamber plasma region 315 or a region in an RPS may be referred toas a remote plasma region. In embodiments, the one or more radicalprecursors, e.g., a radical-fluorine precursor and/or a radical-oxygenprecursor, are created in the remote plasma region and travel into thesubstrate processing region where they may or may not combine withadditional precursors. In embodiments, the additional precursors areexcited only by the radical-fluorine and radical-oxygen precursors.Plasma power may essentially be applied only to the remote plasma regionin embodiments to ensure that the radical-fluorine precursor providesthe dominant excitation. Nitrogen trifluoride or anotherfluorine-containing precursor may be flowed into chamber plasma region215 at rates between about 25 sccm and about 500 sccm, between about 50sccm and about 150 sccm, or between about 75 sccm and about 125 sccm indifferent embodiments.

Combined flow rates of precursors into the chamber may account for 0.05%to about 20% by volume of the overall gas mixture; the remainder beingcarrier gases. The fluorine-containing precursor may be flowed into theremote plasma region, but the plasma effluents may have the samevolumetric flow ratio in embodiments. In the case of thefluorine-containing precursor, a purge or carrier gas may be firstinitiated into the remote plasma region before the fluorine-containinggas to stabilize the pressure within the remote plasma region.

Substrate processing region 333 can be maintained at a variety ofpressures during the flow of precursors, any carrier gases, and plasmaeffluents into substrate processing region 333. The pressure may bemaintained between about 0.1 mTorr and about 100 Torr, between about 1Torr and about 20 Torr or between about 1 Torr and about 5 Torr indifferent embodiments.

Embodiments of the deposition systems may be incorporated into largerfabrication systems for producing integrated circuit chips. FIG. 4 showsone such system 400 of deposition, etching, baking, and curing chambersaccording to disclosed embodiments. In the figure, a pair of frontopening unified pods (“FOUPs”) 402 supply substrates of a variety ofsizes that are received by robotic arms 404 and placed into a lowpressure holding area 406 before being placed into one of the substrateprocessing chambers 408 a-f. A second robotic arm 410 may be used totransport the substrate wafers from the holding area 406 to thesubstrate processing chambers 408 a-f and back. Each substrateprocessing chamber 408 a-f, can be outfitted to perform a number ofsubstrate processing operations including the dry etch processesdescribed herein in addition to cyclical layer deposition, atomic layerdeposition, chemical vapor deposition, physical vapor deposition, etch,pre-clean, degas, orientation, and other substrate processes.

The substrate processing chambers 408 a-f may include one or more systemcomponents for depositing, annealing, curing and/or etching a dielectricfilm on the substrate wafer. In one configuration, two pairs of theprocessing chamber, e.g., 408 c-d and 408 e-f, may be used to depositdielectric material on the substrate, and the third pair of processingchambers, e.g., 408 a-b, may be used to etch the deposited dielectric.In another configuration, all three pairs of chambers, e.g., 408 a-f,may be configured to etch a dielectric film on the substrate. Any one ormore of the processes described may be carried out in chambers separatedfrom the fabrication system shown in different embodiments.

In the preceding description, for the purposes of explanation, numerousdetails have been set forth in order to provide an understanding ofvarious embodiments of the present technology. It will be apparent toone skilled in the art, however, that certain embodiments may bepracticed without some of these details, or with additional details.

Having disclosed several embodiments, it will be recognized by those ofskill in the art that various modifications, alternative constructions,and equivalents may be used without departing from the spirit of thedisclosed embodiments. Additionally, a number of well-known processesand elements have not been described in order to avoid unnecessarilyobscuring the present technology. Accordingly, the above descriptionshould not be taken as limiting the scope of the technology.

Where a range of values is provided, it is understood that eachintervening value, to the smallest fraction of the unit of the lowerlimit, unless the context clearly dictates otherwise, between the upperand lower limits of that range is also specifically disclosed. Eachsmaller range between any stated value or intervening value in a statedrange and any other stated or intervening value in that stated range isencompassed. The upper and lower limits of those smaller ranges mayindependently be included or excluded in the range, and each range whereeither, neither, or both limits are included in the smaller ranges isalso encompassed within the technology, subject to any specificallyexcluded limit in the stated range. Where the stated range includes oneor both of the limits, ranges excluding either or both of those includedlimits are also included.

As used herein and in the appended claims, the singular forms “a”, “an”,and “the” include plural references unless the context clearly dictatesotherwise. Thus, for example, reference to “an operation” includes aplurality of such operations, and reference to “the plate” includesreference to one or more plates and equivalents thereof known to thoseskilled in the art, and so forth.

Also, the words “comprise(s)”, “comprising”, “contain(s)”, “containing”,“include(s)”, and “including”, when used in this specification and inthe following claims, are intended to specify the presence of statedfeatures, integers, components, or operations, but they do not precludethe presence or addition of one or more other features, integers,components, operations, acts, or groups.

The invention claimed is:
 1. A method of etching a patterned substrate,the method comprising: flowing an oxygen-containing precursor into afirst remote plasma region fluidly coupled with a substrate processingregion while forming a plasma in the first remote plasma region toproduce oxygen-containing plasma effluents; flowing afluorine-containing precursor into a second remote plasma region fluidlycoupled in series between the first remote plasma region and thesubstrate processing region while forming a plasma in the second remoteplasma region to produce fluorine-containing plasma effluents, whereinthe fluorine-containing precursor bypasses the first plasma region;flowing the oxygen-containing plasma effluents into the second remoteplasma region during formation of the plasma in the second remote plasmaregion to mix with the fluorine-containing plasma effluents; flowing theoxygen-containing plasma effluents and fluorine-containing plasmaeffluents into the processing region together from the second remoteplasma region; and etching a patterned substrate housed in the substrateprocessing region with the oxygen-containing and fluorine-containingplasma effluents.
 2. The method of claim 1, wherein at least oneadditional precursor is flowed with one or both of the oxygen-containingprecursor or the fluorine-containing precursor, and the additionalprecursor is selected from the group consisting of helium, argon,nitrogen, and molecular hydrogen (H₂).
 3. The method of claim 1, whereinthe fluorine-containing precursor comprises a precursor selected fromthe group consisting of atomic fluorine, diatomic fluorine, nitrogentrifluoride, carbon tetrafluoride, hydrogen fluoride, and xenondifluoride.
 4. The method of claim 3, wherein the fluorine-containingprecursor comprises nitrogen trifluoride, and wherein thefluorine-containing plasma effluents consist essentially of NF* and NF₂*species.
 5. The method of claim 1, wherein the oxygen-containingprecursor comprises a precursor selected from the group consisting ofmolecular oxygen, ozone, nitrous oxide, nitric oxide, and nitrogendioxide.
 6. The method of claim 1, wherein the second remote plasmaregion is configured to produce a capacitively-coupled plasma.
 7. Themethod of claim 6, wherein the plasma in the second remote plasma regionis operated at a power level of less than or about 200 Watts.
 8. Themethod of claim 1, wherein the substrate temperature is maintained at orbelow about 50° C. during the etch process.
 9. The method of claim 1,wherein the first remote plasma region comprises a Remote Plasma System(RPS) unit coupled with the a substrate processing chamber lid assembly.10. The method of claim 1, wherein the operation of flowing theoxygen-containing plasma effluents and fluorine-containing plasmaeffluents into the processing region comprises flowing both plasmaeffluents through a showerhead separating each remote plasma region fromthe substrate processing region.
 11. A method of etching a patternedsubstrate, the method comprising: flowing an oxygen-containing precursorinto a first remote plasma region fluidly coupled with a second remoteplasma region of a substrate processing chamber while forming a plasmain the first remote plasma region to produce oxygen-containing plasmaeffluents; delivering the oxygen-containing plasma effluents into thesecond remote plasma region; flowing a fluorine-containing precursorinto the second remote plasma region while forming a plasma in thesecond remote plasma region to produce fluorine-containing plasmaeffluents, wherein the second remote plasma region is fluidly coupledwith a substrate processing region, and wherein the second remote plasmaregion is fluidly coupled between the first remote plasma region and thesubstrate processing region, and wherein the fluorine-containingprecursor bypasses the first plasma region; delivering theoxygen-containing plasma effluents and fluorine-containing plasmaeffluents into the substrate processing region simultaneously from thesecond remote plasma region; and etching a patterned substrate housed inthe substrate processing region with the oxygen-containing andfluorine-containing plasma effluents.
 12. The method of claim 11,wherein the plasma in the second remote plasma region is acapacitively-coupled plasma.
 13. The method of claim 12, wherein theplasma in the second remote plasma region is operated at a power levelof less than or about 200 Watts.
 14. The method of claim 11, wherein thefirst remote plasma region is operated at a first plasma power and thesecond remote plasma region is operated at a second plasma power, andwherein the first plasma power and second plasma power are differentfrom one another.
 15. A method of etching a patterned, the methodcomprising: flowing an oxygen-containing precursor into a first remoteplasma region fluidly coupled with a second remote plasma region of asubstrate processing chamber while forming a plasma in the first remoteplasma region to produce oxygen-containing plasma effluents; deliveringthe oxygen-containing plasma effluents into the second remote plasmaregion; during delivery of the oxygen-containing plasma effluents intothe second remote plasma region, flowing nitrogen trifluoride into thesecond remote plasma region through an inlet that bypasses the firstremote plasma region while forming a capacitively-coupled plasma in thesecond remote plasma region at a power level of less than or about 200Watts to produce NF* and NF₂* plasma effluents, wherein the secondremote plasma region is fluidly coupled with a substrate processingregion; delivering the oxygen-containing plasma effluents and the NF*and NF₂* plasma effluents into the substrate processing region from thesecond remote plasma region; and etching a patterned substrate housed inthe substrate processing region with the oxygen-containing andfluorine-containing plasma effluents, wherein the substrate processingregion is substantially plasma-free during the etching, and wherein thepatterned substrate has exposed regions of silicon oxide and siliconnitride.